I added the VLA support to clang and lldb about a year ago, so you'll need fairly recent version of both for it to work.
-- adrian > On Feb 17, 2020, at 12:25 PM, Levo DeLellis <levo.delel...@gmail.com> wrote: > > It looks like I wasn't careful and mixed version. I compiled with clang-9 but > used lldb-6. Surprisingly this was the only error I notice when mixing these > version. I could swear I tried compiling with clang-6. I'd double check but > it appears that installing lldb-9 removed lldb(-6) from my system > Thanks for pointing me in the right direction > > On Mon, Feb 17, 2020 at 11:18 AM Adrian Prantl <apra...@apple.com > <mailto:apra...@apple.com>> wrote: > That is interesting. According to LLDB's test/lang/c/vla/* frame variable for > a VLA is supposed to work. Frame variable is also supposed to hide the > __vla_expr0 artificial helper variable. Is this an older LLDB from your > system or an LLDB you built from source? If yes, would you mind filing a > bugreport about this? > > thanks, > adrian > > > On Feb 15, 2020, at 8:17 AM, Levo DeLellis <levo.delel...@gmail.com > > <mailto:levo.delel...@gmail.com>> wrote: > > > > Thanks for the suggestions but it doesn't appear to be working correctly > > for me. I tried building the below after seeing the results with "clang -g > > -std=c99 test.c" and got the same result > > > > LLDB thinks MyArray is 81 elements long even though 81 and 80 doesn't show > > up anywhere in the llvm-ir (I tried again using an llvm ir file made by > > clang -g -std=c99 test.c -S -emit-llvm and clang -g test.ll) > > > > $ cat test.c > > int foo(int s) { > > int MyArray[s]; > > int i; > > for (i = 0; i < s; ++i) > > MyArray[i] = s; > > return 0; > > } > > > > int main(){ > > foo(5); > > return 0; > > } > > $ clang -g test.c > > $ lldb ./a.out > > (lldb) target create "./a.out" > > Current executable set to './a.out' (x86_64). > > (lldb) break set -f test.c -l 6 > > Breakpoint 1: where = a.out`foo + 101 at test.c:7, address = > > 0x0000000000400505 > > (lldb) r > > Process 3205 launched: './a.out' (x86_64) > > Process 3205 stopped > > * thread #1, name = 'a.out', stop reason = breakpoint 1.1 > > frame #0: 0x0000000000400505 a.out`foo(s=5) at test.c:7 > > 4 for (i = 0; i < s; ++i) > > 5 MyArray[i] = s; > > 6 return 0; > > -> 7 } > > 8 > > 9 int main(){ > > 10 foo(5); > > (lldb) frame variable > > (int) s = 5 > > (unsigned long) __vla_expr0 = 5 > > (int) i = 5 > > (int [81]) MyArray = { > > [0] = 5 > > [1] = 5 > > [2] = 5 > > [3] = 5 > > [4] = 5 > > [5] = 0 > > [6] = -136481184 > > [7] = 32767 > > [8] = -8408 > > [9] = 32767 > > [10] = -8544 > > [11] = 32767 > > [12] = 1 > > [13] = 5 > > [14] = 5 > > [15] = 0 > > [16] = -8512 > > [17] = 32767 > > [18] = 0 > > [19] = 5 > > [20] = -8432 > > [21] = 32767 > > [22] = 4195641 > > [23] = 0 > > [24] = -8208 > > [25] = 32767 > > [26] = 0 > > [27] = 0 > > [28] = 4195664 > > [29] = 0 > > [30] = -140485737 > > [31] = 32767 > > [32] = 0 > > [33] = 32 > > [34] = -8200 > > [35] = 32767 > > [36] = 0 > > [37] = 1 > > [38] = 4195616 > > [39] = 0 > > [40] = 0 > > [41] = 0 > > [42] = -1953144313 > > [43] = 1284291557 > > [44] = 4195248 > > [45] = 0 > > [46] = -8208 > > [47] = 32767 > > [48] = 0 > > [49] = 0 > > [50] = 0 > > [51] = 0 > > [52] = 1064657415 > > [53] = -1284291430 > > [54] = 933978631 > > [55] = -1284287451 > > [56] = 0 > > [57] = 32767 > > [58] = 0 > > [59] = 0 > > [60] = 0 > > [61] = 0 > > [62] = -136423629 > > [63] = 32767 > > [64] = -136530376 > > [65] = 32767 > > [66] = 386784 > > [67] = 0 > > [68] = 0 > > [69] = 0 > > [70] = 0 > > [71] = 0 > > [72] = 0 > > [73] = 0 > > [74] = 4195248 > > [75] = 0 > > [76] = -8208 > > [77] = 32767 > > [78] = 4195290 > > [79] = 0 > > [80] = -8216 > > } > > > > > > On Thu, Feb 13, 2020 at 3:53 PM Adrian Prantl <apra...@apple.com > > <mailto:apra...@apple.com>> wrote: > > Take a look at the IR clang produces for C99 variable-length arrays. > > > > -- adrian > > > >> On Feb 13, 2020, at 10:03 AM, Levo DeLellis via llvm-dev > >> <llvm-...@lists.llvm.org <mailto:llvm-...@lists.llvm.org>> wrote: > >> > >> Hi. I searched and the closest thing I could find was this > >> http://lists.llvm.org/pipermail/llvm-dev/2018-February/121348.html > >> <http://lists.llvm.org/pipermail/llvm-dev/2018-February/121348.html> > >> > >> Currently a known sized array looks and debugs as expected. I use > >> llvm.dbg.declare with DICompositeType tag: DW_TAG_array_type and the size > >> field. In my language arrays are always passed around with a pointer and > >> size pair. I'd like debugging to show up as nicely instead of a pointer > >> addr with no information about the elements. How would I do this? I don't > >> use the C API, I output llvm-ir directly. I was hoping I can call > >> llvm.dbg.declare/addr/value to specify the pointer, name and size of the > >> variable but I really have no idea how to pass the size to the debugger. > >> > >> _______________________________________________ > >> LLVM Developers mailing list > >> llvm-...@lists.llvm.org <mailto:llvm-...@lists.llvm.org> > >> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > >> <https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev> > > >
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